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Polylactic acid modified with graphene oxide (PLA/GO) is proposed to interact with ZnO through 6 different schemes. Density functional theory at B3LYP/LANL2DZ level was utilized to calculate total dipole moment (TDM), HOMO/LUMO energy gap (ΔE) and to map the molecular electrostatic potential (MESP). Results indicated that PLA/GO interacted with ZnO through O-atom forming PLA/GO/OZn composite. This composite interacts with methane, hydrogen sulfide, humidity (H2O), carbon dioxide and ethanol. The same gases were supposed to interact further with PLA/GO/Cu2O. Adsorption energy for the interaction between each composite and the proposed gases were calculated. Both PLA/GO/OZn and PLA/GO/Cu2O composites interacted favorably with H2O. Adsorption energy for interaction of other gases with studied structures are generally low compared to H2O. PLA/GO/OZn have adsorption energy slightly higher than that of PLA/GO/Cu2O. PLA/GO/OZn has higher TDM values than those of PLA/GO/Cu2O, indicating a more polar material. Conversely, PLA/GO/Cu2O exhibited larger ΔE values than those of PLA/GO/OZn. TDM and energy gap results for both studied structures indicated good sensing capabilities. Further insights come from analyzing the calculated density of states (DOS) and partial density of states (PDOS). PLA/GO/Cu2O exhibited high peak for copper in its DOS and PDOS spectra compared to zinc and oxygen in case of PLA/GO/OZn. This means a higher density of available electronic states associated with Cu. [ABSTRACT FROM AUTHOR]

The hydrothermal method was used to prepare manganese oxide (Mn2O3) nanoparticles. Reduced graphene oxide (rGO) powder was sonicated with Mn2O3 forming a homogeneous Mn2O3-rGO nanocomposite. The prepared nanocomposite was characterized by UV–Vis spectroscopy to unravel origin of absorption photons strongly in the visible region that ensues due to charge transfer, Fourier transform infrared (FTIR) result reveal that the catalytic role of Mn2O3 in graphene reduction in sono-nano composites formation, X-ray diffraction (XRD) result also stand out all of structural parameters enhance slight increase for the position non-ideality (δ dislocation density) of atoms in crystallite size (D) and micro strain (ε).Decreasing the average crystallite size 41.13 nm and 37.2 nm for Mn2O3 and Mn2O3-rGO respectively due to high (600 W) ultra-sonication in presence of rGO-sheets. Field emission scanning electron microscopy (FESEM) show up uniform distribution of Mn2O3 and tightly anchored on the surface of the rGO sheets. These different characterization techniques confirmed the formation of the nanocomposite. Molecular quantum mechanical calculations for interaction investigation mechanism between rGO and Mn2O3, were conducted. Two model molecules were built for Mn2O3 and functionalized rGO, and 8 possible interaction mechanisms between Mn2O3 and functionalized rGO were proposed. Density functional theory (DFT) calculations using B3LYP/LANL2DZ basis set were conducted for the studied model molecules. Electronic properties and reactivity were investigated by calculating molecular electrostatic potential (MESP) mapping for model structures. The most active and plausible structure is the interaction of rGO through the OH group at the terminal with Mn2O3 through the Mn atom. It can be concluded that Mn2O3 activates the rGO surface and increases its detection sensitivity and reactivity. [ABSTRACT FROM AUTHOR]

Polytetrafluoroethylene (PTFE) is one of the most significant fluoropolymers, and one of the most recent initiatives is to increase its performance by using metal oxides (MOs). Consequently, the surface modifications of PTFE with two metal oxides (MOs), SiO2 and ZnO, individually and as a mixture of the two MOs, were modeled using density functional theory (DFT). The B3LYPL/LANL2DZ model was used in the studies conducted to follow up the changes in electronic properties. The total dipole moment (TDM) and HOMO/LUMO band gap energy (∆E) of PTFE, which were 0.000 Debye and 8.517 eV respectively, were enhanced to 13.008 Debye and 0.690 eV in the case of PTFE/4ZnO/4SiO2. Moreover, with increasing nano filler (PTFE/8ZnO/8SiO2), TDM changed to 10.605 Debye and ∆E decreased to 0.273 eV leading to further improvement in the electronic properties. The molecular electrostatic potential (MESP) and quantitative structure activity relationship (QSAR) studies revealed that surface modification of PTFE with ZnO and SiO2 increased its electrical and thermal stability. The improved PTFE/ZnO/SiO2 composite can, therefore, be used as a self-cleaning layer for astronaut suits based on the findings of relatively high mobility, minimal reactivity to the surrounding environment, and thermal stability. [ABSTRACT FROM AUTHOR]